The purpose of this study is to measure nitric oxide (NO) production in rheumatoid arthritis. A diet low in nitrate and nitrite will be given. Blood, urine, and saliva will be collected for measurement of urinary nitrate/nitrite excretion, iNOS expression by macrophages, NO-hemoglobin by electron paramagnetic resonance, and S-nitrosothiols. These analyses will be used to determine whether increased levels of NO correlate with clinical and laboratory measures of disease activity.